A hydraulic damper of this kind is known from patent application US 2002134629. It includes a compression stroke valve having one or more deflectable discs mounted on the piston on the rebound chamber side and a rebound stroke valve having one or more deflectable discs mounted on the piston on the compression chamber side. The deflectable discs of the compression stroke valve have fluid flow apertures aligned with the rebound flow passage. The compression stroke valve also has an annular stop member and an annular orientation disc positioned between the stop member and the deflectable discs on the side of the deflectable discs remote from the piston. The stop member and the orientation disc have fluid flow apertures aligned with fluid flow apertures in the deflectable discs. An orientation disc has a pin folded therefrom and extending in a direction substantially parallel to the longitudinal axis, the pin extending through corresponding apertures formed in the deflectable discs into a corresponding slot formed in the piston. Alignment means formed on the orientation disc and the stop member for aligning the orientation disc relative to the stop member, allow easier alignment of the compression stroke valve components.
International publication WO 2012/014618 discloses a similar damper provided with: a valve disc for defining the interior of a cylinder in which a working fluid is sealed; a port formed in the valve disc and connecting fluid chambers defined by the valve disc; an annular leaf valve capable of moving in the direction of the axis of the valve disc, the leaf valve being stacked on the valve disc and opening and closing the port according to the pressure difference between the fluid chambers; and a pressing mechanism for pressing the leaf valve in the direction in which the leaf valve closes the port. The pressing mechanism is provided with: a shaft member consisting of a non-magnetic material and having the leaf valve slidably disposed on the outer periphery thereof; and a movable magnet slidably disposed on the outer periphery of the shaft member and pressing, utilizing the magnetic force thereof, the leaf valve toward the valve disc.
Dampers of this kind may easily be provided with two separate mechanisms of generating damping force in dependence of the velocity of the piston rod.
If the speed of the rod is relatively low, working liquid flows from the compression chamber to the rebound chamber or in the opposite direction through appropriate passages of the first and the second piston body members and openings provided in disc or discs of the compression and/or rebound stroke assemblies but none of the discs deflects under the pressure of the working liquid.
Higher pressure of the working liquid that occurs for higher speeds of the piston rod leads to deflection of respective disc assemblies. Now during high speed compression stroke the working liquid flows from the compression chamber mainly through radially outer axial passages of the second piston body member, through the gap between the deflected discs of the compression stroke disc assembly that opens proportionally to the pressure of the working liquid and finally through radially outer axial passage to the rebound chamber. On the other hand, during high speed rebound stroke the working liquid flows mainly from the rebound chamber through radially inner axial passages of the first piston body member, radially inner axial passages of the compression stroke disc assembly, radially inner axial passages of the second piston body member and finally through the gap between the deflected discs of the rebound stroke disc assembly, that opens proportionally to the pressure of the working liquid, to the compression chamber.
Dampers of this kind also provide excellent tuning capabilities. By changing the number, diameters, widths of each disc of the compression and rebound disc assemblies, the number, diameters, widths of the axial passages in the first and the second piston body member and radially inner axial passages of the compression stroke disc assembly, as well as providing, if necessary, rebound and/or compression stroke disc assemblies with low speed rebound and compression openings of varying number and sizes one may define and fine-tune the damping force characteristics independently for a rebound and compression stroke of the damper.
Unfortunately to enable low speed fluid communication between the first and the second piston body member it is necessary not only to provide each disc of the compression stroke disc assembly with an axial passage but more importantly to independently secure angular position of each disc with regard to each other and with regard to the radially inner axial passages of the first and the second piston body member in order to properly align radially inner axial passages of the discs with inner axial passages of these piston body members.
It has been the object of the present invention to provide a damper that would alleviate the aforementioned discs positioning necessity, and therefore would allow for simplification and shortening the time of the damper assembling process, yet would not impose modification of the assembly line, would allow for using as much of the same elements of the piston assembly as possible and would reduce neither the damper performance nor its tuning capabilities.